The duration of each twilight phase depends on the latitude and the time of the year. In locations where the Sun is directly overhead at noon – for example at the Equator during the equinoxes – the Sun traverses the horizon at an angle of 90°, making for swift transitions between night and day and relatively short twilight phases. For example, in Quito, Ecuador, which is very close to the Equator, civil twilight begins only about 21 minutes before sunrise during the equinoxes.

At higher latitudes, in both hemispheres, the Sun’s path makes a lower angle with the horizon, so the twilight phases last longer: